Dampen

You attempt to interrupt a creature in the process of casting a spell or making a melee or ranged attack. If the creature is casting a spell of 3rd level or lower, all damage the spell dealt is halved. If it is casting a spell of 4th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a success, all damage dealt by the creature's spell is halved.

If the creature is making a melee or ranged attack, half all damage dealt by the attack unless the attacker passes a DC:15 check using their attack modifier

At Higher Levels. When you cast this spell using a spell slot of 3th level or higher, it can half the damage of a spell which level is equal to (1 + the level you cast this spell as) without needing an ability check. And a melee or ranged attacker needs to pass a DC of 1 higher per additional level.